The Swamp is like a game knowledge check. I think something doesn't add up with your post though. You don't watch guides, have all the knowledge you could ever need, have the best gear and food available, defeating one of the strongest enemies in the entire game and taming the Plains biome, and then for some reason drive your boat right into the swamp and get overwhelmed by Draugr. It just doesn't make sense.

Draugr are comparable to Greydwarf Brutes, Abominations to Trolls. Bringing the boat in is a huge mistake.

Myself and a friend just made level 1 bronze gear and conquered the swamp without a cauldron(meaning no mead or prepared foods), going on to fight the boss after getting poison resist meads and iron gear. You also shouldn't be dying on the way back to your corpse unless there's like a wraith or something because of how insanely fast you can move while unarmored.

There's something going on with how you guys are playing it, and the losing your boat thing makes it sound like you guys just charge in there with little caution.